0. Formation of covalent bonds in compounds exhibits
(a) wave nature of electron
(b) particle nature of electron
(c) both wave and particle nature of electron
(d) none of these.
1. A strip of copper and another germanium are cooled from room temperature to 80 K. The resistan
(a) each of these decrease
(b) copper strip increases and that of germanium
(c) copper strip decreases and that of germanium increases
(d) cach of these increases.
2. The difference in the variation of resistance with temperature in a metal and a semiconductor aris
essentially due to the difference in the
(a) crystal structure
(b) variation of the number of charge carriers with temperature
(c) type of bonding
(d) variation of scattering mechanism with temperature,
3. In the middle of the depletion layer of a reverse-biased p-n junction, the
(a) electric field is zero
(b) potential is maximum
(c) electric field is maximum
(d) potential is zero.
4. When npn transistor is used as an amplifier
(a) electrons move from base to collector
(b) holes move from emitter to base
(c) electrons move from collector to base
(d) holes moves from base to emitter.
5. For a transistor amplifier in common emitter configuration for load impedance of 1 ks
(hje = 50 and hoe = 25) the current gain is
(a) - 5.21
(b) - 15.2
(c)- 24.8
(d) - 48.78
Answers
Explanation:
1. Conductor -
When there is no energy gap between
valence band and conduction band.
- wherein
1) Very high conductivity.
2) Very high free electron density
Cu, Ag, Au, Na etc.
Bond formation is always due to
overlapping of orbitals. Orbitals
represent distribution of electrons which
is a wave concept of proposed by
debroglie.
Correct option is 1.
2 Correct Option (b) variation of the number of charge carriers with temperature Explanation: Metal has number of free electrons while semiconductor has not at room temperature. The difference in the variation of resistance with temperature in metal and semiconductor is caused due to difference in the variation of the number of charge carriers with temperature.
3. Correct Answer: A
Solution :
Due to the reverse biasing
Free
Videos the width of depletion
region increases and
current flowing through
the diode is almost zero.
In this case electric field
is almost zero at the
middle of the depletion
region.
4. Correct Option (d) holes move from base to emitter
Explanation: When forward bias is applied on n-p-n transistor, then it works as an amplifier in forward biased n-p-n transistor, electrons move from emitter to base and holes move from base to emitter.
5. Correct Option (d) -48.78 Explanation: For a transistor amplifier in common emitter configuration, current gain where, hfe and hoe are hybrid parameters of a transistor.